Olefins, such as ethylene and propylene can be produced by conventional pyrolysis processes, such as steam cracking. Steam cracking involves exposing water and a hydrocarbon having at least two carbon atoms to a temperature in the range of about 600° C. to about 1100° C., a pressure in the range of about 1.5 to 2.75 bar, and a residence time in the range of 0.1 to 0.6 second. See, e.g., Kirk Othmer Encyclopedia of Chemical Technology, Vol. 10, 599-609. The reference discloses that steam cracking feeds comprising butane and light naphtha lead to an increase in the relative amount of propylene in the product. Although the reference discloses optimizing the process for increased propylene production, the relative amount of ethylene in the product is generally much larger than the amount of propylene.
European Patent Application Publication No. EP 1741691A1 discloses a two-step process for producing ethylene. According to that reference, high-temperature hydrocarbon pyrolysis is utilized to produce acetylene. Hydrogen is then thermally transferred from alkane to the acetylene, the hydrogen transfer being conducted at a temperature in the range of 800° C. to 910° C. When the alkane is propane, the hydrogen transfer produces ethylene and propylene.
Hydrocarbon pyrolysis and thermal hydrogen-transfer require a significant amount of energy. Hydrocarbon conversion processes utilizing less energy are desired. In certain cases, it is also desired to increase the relative amount of propylene in the product.